Well that's bad news. Sorry but there's no word about removing the screen in the assembly manual I have...
What about removing the drivers pre-installed gasket together with the screen and applying some of the vinyl caulk? That would minimize the gap between the driver and the mounting plate.
Best, Markus
What about removing the drivers pre-installed gasket together with the screen and applying some of the vinyl caulk? That would minimize the gap between the driver and the mounting plate.
Best, Markus
Use this "vinyl caulk" at your own risk, but I don't like the idea at all.
Just cut out the screen with a sharp knife about 1/4" outside of the aperature. It will then just come right out. Then mount the plate using the gasket provided on the driver. It will crush down to almost nothing. You will then see the gap that I told you about quite a while back - the one on the driver itself and the reason why obsessing about the fit of the mounting plate etc. was not very fruitful. This gap HAS TO be corrected and as such you can then correct any and all fit issues at the same time. I would continue to recommend clay here for all the reasons that I stated. Glues and caulks always have issues. If you must use a caulk make sure that it is water based, like a latex and not silicone based as that cures via releasing acid.
Only the very earliest revision of the assembly manual did not mention cutting out the screen. The manual is now very clear on this issue.
Just cut out the screen with a sharp knife about 1/4" outside of the aperature. It will then just come right out. Then mount the plate using the gasket provided on the driver. It will crush down to almost nothing. You will then see the gap that I told you about quite a while back - the one on the driver itself and the reason why obsessing about the fit of the mounting plate etc. was not very fruitful. This gap HAS TO be corrected and as such you can then correct any and all fit issues at the same time. I would continue to recommend clay here for all the reasons that I stated. Glues and caulks always have issues. If you must use a caulk make sure that it is water based, like a latex and not silicone based as that cures via releasing acid.
Only the very earliest revision of the assembly manual did not mention cutting out the screen. The manual is now very clear on this issue.
They will tell you not to do it or won't reply at all. In fact I would never do it on any system that doesn't have a foam plug as a completly open throat is going to be a problem. The foam plug does the same thing as the screen so removing it in this case is not a problem.
You can get replacement foam gasket material at Michaels or the like. Its just thin foam with adhesive backing. This part is applied at the factory in Italy and I doubt that either Parts Express or B&C NA will have it. Why would they?
You can get replacement foam gasket material at Michaels or the like. Its just thin foam with adhesive backing. This part is applied at the factory in Italy and I doubt that either Parts Express or B&C NA will have it. Why would they?
This is how it looks like when you cut out the screen:
There are still fibers sticking into the throat. So I decided to remove the gasket completely by first scraping the foam off with a sharp knife and then removing the glue with cleaning alcohol:
Now you have much better control over the gap that needs to be filled.
Earl, why are you recommending clay over vinyl caulk? It's specifically made for such jobs and allows water cleanup (silicone doesn't)? Furthermore it was completely removable from the acrylic mounting plate with cleaning alcohol.
Best, Markus
An externally hosted image should be here but it was not working when we last tested it.
There are still fibers sticking into the throat. So I decided to remove the gasket completely by first scraping the foam off with a sharp knife and then removing the glue with cleaning alcohol:
An externally hosted image should be here but it was not working when we last tested it.
Now you have much better control over the gap that needs to be filled.
Earl, why are you recommending clay over vinyl caulk? It's specifically made for such jobs and allows water cleanup (silicone doesn't)? Furthermore it was completely removable from the acrylic mounting plate with cleaning alcohol.
Best, Markus
Markus
You seem intent on not doing things the way I suggest. I said to cut back the foam gasket by 1/4" in which case the screen would have come completely out and there would be no fibers in the throat. There was no need to completely remove the gasket (and I surely would not recommend this practice) and now you are into techniques which I have never tried and cannot comment on.
I have never heard of vinyl caulk so how can I comment on its use. (Actually just looked it up on the web - its an adhesive and is definately NOT what you want. I would not glue the driver in as there is absolutely no reason to do that. You want a gasket NOT an adhesive.)
I have used clay for five years now and it works fine.
I would recommend getting some foam, making a new gasket and using clay.
You seem intent on not doing things the way I suggest. I said to cut back the foam gasket by 1/4" in which case the screen would have come completely out and there would be no fibers in the throat. There was no need to completely remove the gasket (and I surely would not recommend this practice) and now you are into techniques which I have never tried and cannot comment on.
I have never heard of vinyl caulk so how can I comment on its use. (Actually just looked it up on the web - its an adhesive and is definately NOT what you want. I would not glue the driver in as there is absolutely no reason to do that. You want a gasket NOT an adhesive.)
I have used clay for five years now and it works fine.
I would recommend getting some foam, making a new gasket and using clay.
Well, now you're in the comfortable position to state "I told him to use clay instead of something else. So it's completely his fault that his speaker sound that bad" 
Here's how I proceeded - applied vinyl caulk aroung the compression drivers throat:
Screwed the mounting plate on:
Remove the excess of caulk. Wet your finger with water and smooth the joint between mounting plate and driver throat:
Best, Markus
Here's how I proceeded - applied vinyl caulk aroung the compression drivers throat:
An externally hosted image should be here but it was not working when we last tested it.
Screwed the mounting plate on:
An externally hosted image should be here but it was not working when we last tested it.
Remove the excess of caulk. Wet your finger with water and smooth the joint between mounting plate and driver throat:
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
Markus
Did you apply something to the surfaces to prevent them from sticking? If thats a good adhesive, I really hope that you don't have to replace the driver.
I simply could not recommend this practice as drivers do need to be replaced occasionally and you could have trouble getting that joint appart. If others insist on doing things this way then make sure and put a thin film of lubricant on both surfaces, or at least one. This will make future seperation much easier.
I simply don't understand the attraction to using glue.
Did you apply something to the surfaces to prevent them from sticking? If thats a good adhesive, I really hope that you don't have to replace the driver.
I simply could not recommend this practice as drivers do need to be replaced occasionally and you could have trouble getting that joint appart. If others insist on doing things this way then make sure and put a thin film of lubricant on both surfaces, or at least one. This will make future seperation much easier.
I simply don't understand the attraction to using glue.
Markus,
I believe the use of the clay has been stated many times.
Geddes replies have stated continued flexibility and no off-gassing during 'cure' as the reasons for the clay versus other unknown materials.
I am sure that clay is not the only material that can be used but it is what the man is recommending so I would use it and be done with it.
I believe the use of the clay has been stated many times.
Geddes replies have stated continued flexibility and no off-gassing during 'cure' as the reasons for the clay versus other unknown materials.
I am sure that clay is not the only material that can be used but it is what the man is recommending so I would use it and be done with it.
Well to destroy such a B&C driver you have to put in an awful amount of power, resulting in very high soundpressure levels, I cannot imagine anyone needing that much decibels in a home environment. Remember these B&C units are ussualy used in speakers to cover up audiences of 200 people or more!
Best regards,
Walt
Best regards,
Walt
Walt, please don't let us start from Adam and Eve. Read Earls approach to system design
Earl, it's like I already statet in Post #725: "Furthermore [the vinyl caulk] was completely removable from the acrylic mounting plate with cleaning alcohol.". So I believe this stuff is superior to using clay. It fills, seals and bonds at the same time. But time will tell...
By the way, have you guys ever wondered what's behind the screen of the compression driver? Here it is:
The plastic looks dirty but that seems to be only a cosmetic problem. There are 2 circumferential burrs. They seem to be intentional. Maybe Earl can comment on that?
Best, Markus
Earl, it's like I already statet in Post #725: "Furthermore [the vinyl caulk] was completely removable from the acrylic mounting plate with cleaning alcohol.". So I believe this stuff is superior to using clay. It fills, seals and bonds at the same time. But time will tell...
By the way, have you guys ever wondered what's behind the screen of the compression driver? Here it is:
An externally hosted image should be here but it was not working when we last tested it.
The plastic looks dirty but that seems to be only a cosmetic problem. There are 2 circumferential burrs. They seem to be intentional. Maybe Earl can comment on that?
Best, Markus
First, I don't expect the B&C drivers to fail, but I have seen new units that didn't work - no problem, just R&R it and your back in business. And I have seen numerous driver failures from these systems in clubs (the bigger Summas actually). In a home that's not likeley to occur however.
Marcus
I'm unclear on what your link to my white paper is supposed to be for.
Removing the glue from the surface is different than seperating the two parts once they are glued together. And screwing down the mounting to squize out the material will tend to make it bond to the two surfaces very well. I simply don't like glueing in the driver thats all. Its not necessary.
You should point out the narrow ridge in the driver right at the throat. Its about 1/16" wide by 1/16" deep and has to be filled in after the part is screwed to the mounting plate. Does your vinyl shrink? If it does then there will still be a small dimple when it dries. Clay won't do that.
The ridges are, I believe, mold marks on the phase plug. I don't think that its intentional.
Marcus
I'm unclear on what your link to my white paper is supposed to be for.
Removing the glue from the surface is different than seperating the two parts once they are glued together. And screwing down the mounting to squize out the material will tend to make it bond to the two surfaces very well. I simply don't like glueing in the driver thats all. Its not necessary.
You should point out the narrow ridge in the driver right at the throat. Its about 1/16" wide by 1/16" deep and has to be filled in after the part is screwed to the mounting plate. Does your vinyl shrink? If it does then there will still be a small dimple when it dries. Clay won't do that.
The ridges are, I believe, mold marks on the phase plug. I don't think that its intentional.
tinitus said:
Or maybe some clay
I have told B&C about this on a couple of occasions, but to fix it would require a new mold (lots of money) and they say that no one else has complained (I have to wonder why that is).
I have some designs that have a lip that would go into this gap and fill it and also remove the problem of poor tollerances at the throat. But the part would be expensive to make because of the high tollerences that would be required. If I were to make these systems in large quantities I would certainly change this point in the design, but in the current quantities the current approach is the only viable solution that I have found.
The vinyl caulking is not a strong adhesive and does not bond very strongly to metal or plastic. The plate will be easy to separate from the driver with a thin bladed knife or razor blade. And once it is cured it will easily peel off leaving very little residue to clean up. Other than the acid and out gassing issues I think the vinyl caulking will help damp any vibrations in the plastic mounting flange. And may only improve the sound quality. It does stay reasonably compliant over a few years if it is not exposed to UV.
Thanks, I've never used the stuff so I had no idea.
The plastic plate is rigidly clamped between two hard surfaces, I don't think that vibration would be much of an issue.
I guess if I were doing things this way I'd use Latex caulk since I know that it won't stick very well and it also won't outgas anything offensive. But please, don't just use something at random in this situation as bad things could happen.
The plastic plate is rigidly clamped between two hard surfaces, I don't think that vibration would be much of an issue.
I guess if I were doing things this way I'd use Latex caulk since I know that it won't stick very well and it also won't outgas anything offensive. But please, don't just use something at random in this situation as bad things could happen.
Sorry, got called away and hit the send button.
Is that an edge that might be source for diffraction causing HOMs?
An externally hosted image should be here but it was not working when we last tested it.
Is that an edge that might be source for diffraction causing HOMs?
I believe the answer is "yes" but Dr Geddes will have to answer authoratatively. Five years ago there was a spirited discussion about a redesigned phase plug that he's patented IIRC. Later the psychoacoustic studies that he and his wife performed indicated that the distortion caused by the imperfect phase plugs was present but audible.
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